This invention relates to an infrared suppression system for a gas turbine engine and, more particularly, to an infrared suppression system for a gas turbine engine wherein three separate sources of airflow are utilized for suppression and a direct line of sight to the core engine is eliminated.
In military aircraft gas turbine engines, it is highly desirable that infrared emissions from the engine be reduced to a practical minimum to avoid acquisition and tracking by heat seeking, hostile forces, or to permit effective countermeasures such as evasive action to be taken against such forces. Infrared suppressors have been utilized in conjunction with aircraft gas turbine engines for reducing the level of infrared radiation emitted from the engine exhaust. Such suppressors, however, have generally utilized only one source of airflow to cool the engine exhaust temperatures. In addition, variable geometry has been used to selectively activate the suppressor and block a direct line of sight into the core engine. Variable geometry, however, increases the weight and complexity of the engine with a corresponding decrease in reliability and overall system performance. Further, such systems have generally included centerplugs or vanes in the exhaust path which decrease engine performance due to a buildup of power turbine back pressure.
Therefore, it is a primary object of this invention to provide a simple and reliable infrared suppression system for an aircraft gas turbine engine wherein the system will operate continuously without having to be selectively actuated by the aircraft pilot.
If is a further object of this invention to provide an infrared suppression system for a gas turbine engine which may be readily detached from the engine when infrared suppression is not desired and readily attached to the engine when infrared suppression is desired.
It is also an object of this invention to provide an infrared suppression system for a gas turbine engine wherein the suppressor blocks any direct line of sight into the core engine without the use of variable geometry.
It is a further object of this invention to provide an infrared suppression system for a gas turbine engine wherein the suppressor utilizes the cooling airflow from a plurality of sources.
It is also an object of this invention to minimize the power turbine back pressure of gas turbine engines employing infrared suppression systems by eliminating any items in the exhaust path such as vanes or centerplugs.